Usefulness of the temporal analysis and the normalized difference in the study of rice by means of landsat‐5 TM images: Identification and inventory of rice fields

The multispectral and multitemporal analysis of the spectral response of rice has made it possible to determine at which point in the vegetative cycle of rice it is best to make an inventory, together with the usefulness of the normalized‐difference vegetation index for such an inventory. The results could be usefully included in any classification procedure of the TM image in order to make the inventory in a systematic way. In this case a supervised classification of the image has been made which assumes a Gaussian behaviour for each spectral class. The results obtained are, for the most part, consistent with those obtained by using traditional methods.     

Geochemistry of Cretaceous Magmatism in Eastern Cuba: Recycling of North American Continental Sediments and Implications for Subduction Polarity in the Greater Antilles Paleo-arc

We present whole-rock major- and trace-element and Nd–Sr–Pbradiogenic isotope data for Cretaceous igneous suites from easternCuba. These rocks are related to the Greater Antilles paleo-islandarc magmatism and have three different igneous styles. Group1 consists of tholeiitic basalts and rare basaltic andesitesthat have normal mid-ocean ridge basalt (N-MORB)-like compositionssimilar to those found in back-arc basin basalts (TiO₂ = 1·2–2·9wt%; La/Yb_(N) = 0·7–0·9, Th/Nb = 0·06–0·08,and initial ²⁰⁸Pb/ ²⁰⁴Pb = 37·65–37·74).Group 2 comprises basaltic and rare basaltic andesitic subvolcanicdykes with major- and trace-element and isotopic compositionssimilar to those of island arc tholeiites (TiO₂ = 0·7–1·4wt%; La/Yb_(N) = 0·6–0·9, Th/Nb = 0·06–0·68,and initial ²⁰⁸Pb/ ²⁰⁴Pb = 37·74–38·25).Group 3 is composed of low-Ti (TiO₂ = 0·3–0·9wt%) calcalkaline igneous rocks that have an unambiguous subduction-relatedcharacter (La/Yb_(N) = 1·1–5·0, Th/Nb = 0·35–1·55,and initial ²⁰⁸Pb/ ²⁰⁴Pb = 37·94–38·39).The parental magmas of the three groups formed by variable meltingdegrees (< 5–25%) of spinel lherzolite, with more depletedmantle sources for Groups 2 and 3 than Group 1. The trace-elementand radiogenic isotope compositions of primitive Group 3 samplesare strongly bimodal. One subgroup of samples is characterizedby low Ta/Yb (0·02–0·03) and Th/La (0·10–0·13),slightly subchondritic Nb/Ta (13·3–17·3),and relatively high initial ²⁰⁶Pb/²⁰⁴Pb (18·57–18·62)and _Nd (7·6–9·4). The remaining primitiveGroup 3 samples have higher Ta/Yb (0·06–0·11)and Th/La (0·24–0·32), and highly subchondriticNb/Ta (7·6–9·1), coupled with lower initial²⁰⁶Pb/²⁰⁴Pb (18·24–18·29) and _Nd (3·4–5·5).These signatures were induced by two distinct slab componentsthat mainly reflect the contributions of Cretaceous Atlanticmarine and North American continental sediments, respectively.Nb/Ta in the first subgroup was influenced by melting of rutile-bearingsubducted crust, whereas in the second it was inherited fromrecycled continental sediments. The involvement of Atlanticand North American sediments in Cuban Cretaceous magmatism indicatesthat the Proto-Caribbean (North American-Proto Atlantic) lithospheresubducted beneath the Greater Antilles arc during the Late Cretaceous(pre-Campanian), consistent with geotectonic models involvingonset of SW-dipping subduction beneath the Greater Antillespaleo-arc during the Aptian. The variable mantle source depletionand magnitude of the subduction component probably reflect differentsettings across the arc, from the arc front to a back-arc spreadingridge. KEY WORDS: eastern Cuba; Greater Antilles paleo-island arc; mantle source depletion; Nb/Ta fractionation; slab component     

Improved atmospheric circulation over Europe by the new generation of CMIP6 earth system models

Global Climate Models (GCMs) generally exhibit significant biases in the representation of large-scale atmospheric circulation. Even after a sensible bias adjustment these errors remain and are inherited to some extent by the derived downscaling products, impairing the credibility of future regional projections. In this study we perform a process-based evaluation of state-of-the-art GCMs from CMIP5 and CMIP6, with a focus on the simulation of the synoptic climatological patterns having a most prominent effect on the European climate. To this aim, we use the Lamb Weather Type Classification (LWT, Lamb British isles weather types and a register of the daily sequence 736 of circulation patterns 1861-1971. METEOROL OFF, GEOPHYS MEM; 737 GB; DA 1972; NO 116; PP 1-85; BIBL 2P1/2, 1972), a subjective classification of circulation weather types constructed upon historical simulations of daily mean sea level pressure. Observational uncertainty has been taken into account by considering four different reanalysis products of varying characteristics. Our evaluation unveils an overall improvement of salient atmospheric circulation features consistent across observational references, although this is uneven across models and large frequency biases still remain for the main LWTs. Some CMIP6 models attain similar or even worse results than their CMIP5 counterparts, although in most cases consistent improvements have been found, demonstrating the ability of the new models to better capture key synoptic conditions. In light of the large differences found across models, we advocate for a careful selection of driving GCMs in downscaling experiments with a special focus on large-scale atmospheric circulation aspects.

     

Trace Element Determination of Single Fluid Inclusions in Quartz by Laser Ablation ICP-MS

Single fluid inclusions in quartz from a Pb-Zn-Ag carbonate replacement deposit were selected for trace element determination by laser ablation ICP-MS. Spikes in element intensities were noted between first breached fluids versus subsequent analyses, suggesting that accurate element concentrations may not be determined in smaller fluid inclusions when only one analysis is obtained before the fluid is exhausted. Elemental concentrations in the fluid inclusions were determined by external standardisation using solutions sealed in microcapillary tubes. Standards and single natural inclusion analyses give repeatabilities (%RSD) of ˜ 20% for Rb and Sr. Rubidium and strontium concentrations range from 0.56-5.07 μg ml^-1 and 1.12-27.4 μg ml^-1, respectively, whereas Zn and Ag are below detection limits (< 10 ng ml^-1). The results suggest that nearly all Zn and Ag are removed by the time hydrothermal fluids precipitate gangue minerals.     

Oxidative stress, genotoxicity and histopathology biomarker responses in mullet (Mugil cephalus) and sea bass (Dicentrarchus labrax) liver from Bizerte Lagoon (Tunisia)

The aim of the study was to evaluate the impact of environmental contaminants on oxidative stress, genotoxic and histopathologic biomarkers in liver of mullet (Mugil cephalus) and sea bass (Dicentrarchus labrax) collected from a polluted coastal lagoon (Bizerte Lagoon) in comparison to a reference site (the Mediterranean Sea). Antioxidant enzyme activities were lower in fish from the polluted site compared with fish from the reference site, suggesting deficiency of the antioxidant system to compensate for oxidative stress. DNA damage was higher in both fish species from the contaminated site indicating genotoxic effects. The liver histopathological analysis revealed alterations in fish from Bizerte Lagoon. Hepatocytes from both fish species featured extensive lipid-type vacuolation and membrane disruption. Results suggest that the selected biomarkers in both fish species are useful for the assessment of pollution impacts in coastal environments influenced by multiple pollution sources.     

Synthetic observations using POLARIS: an application to simulations of massive prestellar cores

Astrophysics and Space Science - Dynamical evolution of galaxies is a complex process, especially the centers. Gravitationally coupled gas and stellar discs have been observed to coexist in the...     

Civil nuclear power at risk of tsunamis

Tsunamis have caused severe destruction to vulnerable populations through the ages. Commonly generated from oceanic subduction zones, they still remain difficult to predict. Recent instrumental record on risk of occurrence can be enhanced when complemented by historical, archeological, and geological studies. We assessed the coast at risk and overlaid civilian nuclear sites active, in expansion and under construction. The worldwide distribution of threatened nuclear sites revealed a clustering in South and South-East Asia. We identified four areas for urgent policy attention, including the need for funding to translate scientific risks assessment into effective policy.